Voltage is the difference in electrical potential between two points in space. It is a measure of the amount of energy gained or lost by moving a unit of positive charge from one point to another. Voltage is measured in units of Joules per Coulomb, known as a Volt (V). It is important to remember that voltage is not an absolute quantity; rather, it is always considered as a relative value between two points. In an electronic circuit, the electromagnetic problem of voltages at arbitrary points in space is typically simplified to voltages between nodes of circuit components such as resistors, capacitors, and transistors.